The present invention relates generally to movement of fluids, such as wellbore fluids, and particularly to a technique for lowering the viscosity of a fluid to permit more efficient production of the fluid.
When pumping viscous fluids, the performance of certain pumps, such as centrifugal pumps, is considerably degraded. For example, the pump head and rate of production are decreased while the horsepower requirement increases drastically. This leads to substantially reduced efficiency of the pump. In certain pumping applications, such as in the production of oil, this low efficiency can add considerably to the cost of oil production or even inhibit the ability to produce from the region.
Attempts have been made to lower the fluid viscosity prior to pumping. For example, electric heaters have been used in combination with electric submersible pumping systems to heat the oil prior to being drawn into the submersible pump of the overall system. With electric heaters, however, electricity must be supplied downhole by, for example, a power cable. Other attempts to lower viscosity have included the injection of relatively hot vapor or the use of downhole combustion to generate heat. Each of these approaches can add undesirable cost and complexity depending on the particular environment and application.
The present invention relates generally to a technique for lowering the viscosity of a fluid prior to pumping the fluid. The technique is particularly amenable for use in a downhole environment for the production of oil. The viscous fluid is passed through a viscosity handler prior to being drawn into the production pump which moves a desired fluid from one location to another. The viscosity handler utilizes a movable component that is rapidly and repetitively moved through the fluid. Part of this kinetic energy is translated to the surrounding oil in the form of heat. The heat, in turn, lowers the viscosity of the fluid to permit more efficient production of the fluid by the production pump.